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Old 22nd October 2011, 07:24 AM   #1
ksbluesfan
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UV protection of auto glass

In the US, are there standards of UVA and UVB protection on auto glass? My wife read an article that claimed only UVB protection is provided. A dermatologist claimed that people tend to get skin cancer on their left side due to the driver's seat being on the left in the US. I couldn't find anything through google.
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Old 22nd October 2011, 07:51 AM   #2
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Any glass stops about 90% of UV in home window thickness. Auto glass is about twice as thick.

Plastics are different, Some stop it all, some stop none, others only A or B.

Why would I know? Home brewing. So, I'll add some OT: since any glass stops most UV, it's a fact that amber beer bottles stop blue light that prevents beer from getting 'skunky'. Clear or green bottles will contain Skunky beers. Except Miller, who uses hops extract that has had the skunk pre-curser removed. Bottle glass absorbency: http://realbeer.com/spencer/bottle.html
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Old 22nd October 2011, 01:15 PM   #3
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Originally Posted by ksbluesfan View Post
In the US, are there standards of UVA and UVB protection on auto glass? My wife read an article that claimed only UVB protection is provided. A dermatologist claimed that people tend to get skin cancer on their left side due to the driver's seat being on the left in the US. I couldn't find anything through google.
I don't believe so. I worked at a Pilkington plant where they made car windshields and I don't recall any standards on UV protection (at no point in the process is it measured for control to a standard)

Windshields have a PVB laminate and block about 99% of UV rays, but I'm pretty sure that's in the UVB range. Some of the shade band might block UVA, but for the most part I believe UVA protection is usually done using a coating, which windshields don't have.
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Old 22nd October 2011, 01:24 PM   #4
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UV B, in the range of about 280-315nm, is blocked by any normal glass or just about any material, including skin. Normal float glass 2 to 2.5mm thick will block roughly 40% of the UV A light, which is about 315-400nm.

I don't know about auto glass specifically, but I would think that with the double layers of glass and the laminate between the two, the UV blocking would be higher. Just a rough guess would be in the 70% range.

I wouldn't worry too much about it. Have you ever gotten a sunburn in your car?
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Old 22nd October 2011, 03:47 PM   #5
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Originally Posted by ksbluesfan View Post
In the US, are there standards of UVA and UVB protection on auto glass? My wife read an article that claimed only UVB protection is provided. A dermatologist claimed that people tend to get skin cancer on their left side due to the driver's seat being on the left in the US. I couldn't find anything through google.
Most of that occurs because a LOT of people (myself included) tend to drive a lot in the Spring/Early Summer/Fall with the window down and the arm resting on the sill*.











*I can only speak for the Southwest (NM, W. Tx.) and Colorado...
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Old 22nd October 2011, 03:56 PM   #6
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Originally Posted by rwguinn View Post
Most of that occurs because a LOT of people (myself included) tend to drive a lot in the Spring/Early Summer/Fall with the window down and the arm resting on the sill*.











*I can only speak for the Southwest (NM, W. Tx.) and Colorado...
agree. any time I'm not running the air conditioning or heater in the car it's windows down, arm on the sill time.
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Old 22nd October 2011, 03:59 PM   #7
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Originally Posted by FramerDave View Post
I don't know about auto glass specifically, but I would think that with the double layers of glass and the laminate between the two, the UV blocking would be higher. Just a rough guess would be in the 70% range.
wiki does: Laminated glass
The PVB interlayer also gives the glass a much higher sound insulation rating, due to the damping effect, and also blocks 99% of incoming UV radiation.

The amount of energy is dependent on the wavelength.

Some windshields, like those on the Escalade use EVA instead of PVB. I can't find any specific information on EVA laminated glass but I don't think it blocks any more UVA than PVB. AFAIK IMO
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Old 22nd October 2011, 04:40 PM   #8
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Originally Posted by Furcifer View Post
wiki does: Laminated glass
The PVB interlayer also gives the glass a much higher sound insulation rating, due to the damping effect, and also blocks 99% of incoming UV radiation.

The amount of energy is dependent on the wavelength.

Some windshields, like those on the Escalade use EVA instead of PVB. I can't find any specific information on EVA laminated glass but I don't think it blocks any more UVA than PVB. AFAIK IMO
That probably settles it. Plain glass blocks UVB light just by being glass. According to your info above, laminated glass filters out 99%, which we can take to mean UVB.

Look at it this way: If the glass allowed in significant amounts of UV energy of any type, your car interior furnishings would fade, crack and otherwise deteriorate much much faster then they do.
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Old 22nd October 2011, 04:53 PM   #9
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All I know is it blocks enough to keep my Transition (TM) lenses from darkening.
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Old 25th October 2011, 02:46 PM   #10
ksbluesfan
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According to the NY Times, UVA is not blocked. This article was from April and has a link to two scientific studies.

Article:
http://www.nytimes.com/2011/04/05/health/05really.html

Studies:
http://www.ncbi.nlm.nih.gov/pubmed/20226568
http://download.journals.elsevierhea...2210008522.pdf

I'm surprised. That seems like something that would be provided without much thought.

Last edited by ksbluesfan; 25th October 2011 at 02:48 PM.
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Old 25th October 2011, 05:42 PM   #11
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Isn't UVA less dangerous anyway, due to the longer wavelength? I guess it penetrates deeper though, even if it has less energy...
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